Multi-band single-carrier modulation

ABSTRACT

Multi-band single-carrier modulation. A novel approach is presented by which interference compensation may be performed for signals received by a piconet operable device. The piconet operable device may be implemented within a region that includes two or more SOPs (Simultaneously Operating Piconets). Estimation of the level and location of interference is performed and the input to a decoder (within the piconet operable device) is selectively weighted to ensure that the effect of any existent interference within the signal received by the piconet operable device is minimized. Different interference levels are dealt with differently. For one example, portions of the received signal having undergone a large amount of interference may be simply treated as erasures with respect to the input the decoder. For another example, portions of the received signal having undergone some smaller degree of interference, but some interference nonetheless, may be de-weighted before being provided to the decoder.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 119(e) to the following U.S. Provisional Patent Applicationswhich are hereby incorporated herein by reference in their entirety andmade part of the present U.S. Utility Patent Application for allpurposes:

1. U.S. Provisional Application Ser. No. 60/488,623, entitled “UWB(Ultra Wide Band) interference mitigation,” (Attorney Docket No.BP3085), filed Jul. 18, 2003 (Jul. 18, 2003), pending.

2. U.S. Provisional Application Ser. No. 60/494,498, entitled“Multi-band single-carrier modulation,” (Attorney Docket No. BP3135),filed Aug. 12, 2003 (Aug. 12, 2003), pending.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates generally to communication systems; and, moreparticularly, it relates to receive processing (demodulation anddecoding) of signals received within such communication systems.

2. Description of Related Art

Data communication systems have been under continual development formany years. In recent years, the development of piconet typecommunication systems has been under increasing development. A piconetmay be viewed as a network that is established when two devices connectto support communication of data between themselves. These piconetstypically operate within a region having a radius of up to approximately10 meters. Sometimes, piconets are referred to as PANs (Personal AreaNetworks), and those piconets that operate using wireless means areoften referred to as WPANs (Wireless Personal Area Networks).

Piconets are often typically discussed in the context of wirelesscommunication systems. Devices operating within the piconet typicallyoperate according to an M/S (Master/Slave) type relationship. Somepiconets also include multiple user devices (e.g., slave devices) thatinteract with a piconet controller (e.g., the master device). In evensome other instances, two or more piconets operate such that they shareat least one common device in a scatternet implementation. For example,in a scatternet, user devices (slave devices) may interact with two ormore separate piconet controllers (master devices). This implementationallows various devices within different piconets that are locatedrelatively far from one another to communicate through the correspondingpiconet controllers (master devices) of the scatternet. However, withina scatternet implementation, a problem may arise such that each of theindividual piconets must be able to operate in relative close proximitywith other piconets without interfering with one another. It is alsonoted that independently operating piconets, not implemented within ascatternet implementation, may also suffer from deleterious effects ofinterference with other piconets located within relative closeproximity. One such deleterious effect that may arise is when thesymbols (or pulses) being transmitted within the piconets operatingwithin relatively close proximity collide with one another therebyresulting in potentially lost data.

As is known, the Bluetooth® communication standard is the first such PANcommunication standard that has been developed. In accordance with theBluetooth® communication standard, the communication between the variousdevices in such a piconet is strictly performed using an M/S(Master/Slave) configuration. Each of the devices within the Bluetooth®piconet is M/S capable. Typically one of the devices, or a first devicewithin the Bluetooth® piconet, transmits a beacon signal (or an accessinvitation signal) while operating as the “master” device of theBluetooth® piconet to the other “slave” devices of the Bluetooth®piconet. In other words, the “master” device of the Bluetooth® piconetpolls the other “slave” devices to get them to respond.

Another PAN communication standard that has been developed is that ofthe IEEE (Institute of Electrical & Electronics Engineers) 802.15standard. Variations and extensions of the 802.15 standard (e.g.,802.15.1, 802.15.2, 802.15.3, and others that may be developed overtime) have also been under development during recent times. Operationaccording to 802.15.3 differs from that of the Bluetooth® communicationstandard. According to 802.15.3, one particular device is speciallydesigned to operate as a piconet controller (master) within a piconet;that is to say, every device in such an IEEE 802.15.3 piconet does notoperate in an M/S mode. One device within such an IEEE 802.15.3 piconetoperates as a piconet controller (master), and the other devices withinthe IEEE 802.15.3 piconet may be implemented as user devices (slaves).It is also noted that the piconet controller (master) may operate tofacilitate the p2p (peer to peer) operation between the various userdevices (slaves) within the piconet.

There has been a great deal of development recently in seeking to enablethe simultaneous operation of piconets within relatively close proximitywith one another (without suffering significant deleterious effects suchas degradation of performance, large numbers of collisions oftransmitted symbols within the various piconets, and other suchdeleterious effects. Currently, there does not exist in the art asufficient solution that may accommodate the undesirable effects ofsymbol collisions within such piconets in a satisfactory manner. Whilethere have been some attempts to try to deal with minimizing theseundesirable symbol collisions within such piconets, there does not yetexist a satisfactory manner in which symbol collisions (when they do infact occur) may be dealt with while maintaining a very high level ofperformance for all of the devices within the piconet.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the invention can be found in a communication devicethat operates within a piconet. This communication device may be viewedas being a piconet operable device. The piconet operable device includesa radio front end, an ADC (Analog to Digital Converter), a demodulator,and a decoder. The radio front end receives and filters a continuoustime signal. The ADC samples the received and filtered continuous timesignal thereby generating a discrete time signal and extracting I, Q(In-phase, Quadrature) components there from. The demodulator receivesthe I, Q components and performs symbol mapping of the I, Q componentsthereby generating a sequence of discrete-valued modulation symbols. Thedemodulator estimates at least one of a location and a level ofinterference associated with a collision within a symbol of the sequenceof discrete-valued modulation symbols. The demodulator then categoriesthe level of the interference into at least two categorizes. When thelevel of the interference is categorized into a first category of the atleast two categorizes, the demodulator treats interference affected bitsof the symbol as erasures thereby generating a first demodulator outputsymbol. However, when the level of the interference is categorized intoa second category of the at least two categorizes. The demodulator alsoselectively de-weights interference affected bits of the symbolaccording to a de-weighting factor thereby generating a seconddemodulator output symbol. The decoder decodes the first demodulatoroutput symbol or the second demodulator output symbol to make bestestimates of the at least one information bit contained therein.

In certain embodiments, the demodulator estimates interferenceassociated with the collision within the symbol on a power per bitbasis. The location of interference associated with the collision withinthe symbol may be used to identify the interference affected bits of thesymbol. The demodulator may be implemented in a variety of different ofways; one of which is when the demodulator is implemented as a basebandprocessor/MAC (Medium Access Controller) within the piconet operabledevice.

The piconet operable device may be viewed as being a first piconetoperable device that operates within a first piconet that substantiallyoccupies a first region, and a second piconet operable device operateswithin a second piconet that substantially occupies a second region.These two piconets may be viewed as SOPs (Simultaneously OperatingPiconets), and sometimes the first region and the second region occupyat least a portion of common space. In this SOP context, the symbol maybe viewed as being a first symbol that collides with a second symbolthat is received by the second piconet operable device before beingreceived. Collisions between symbols within the first piconet andsymbols within the second piconet can occur according to a structuredinterference pattern. Sometimes, this structured interference pattern isa predetermined structured interference pattern, and the demodulatorestimates at least one of the location and the level of interferenceassociated with the collision within the symbol based on thepredetermined structured interference pattern.

In some instances, the demodulator estimates the level of interferenceassociated with the collision within the symbol by measuring a totalinstantaneous power of the continuous time signal associated with thesymbol, averaging a power of the continuous time signal associated withthe symbol, and subtracting an expected reference signal powerassociated with the symbol from a previously obtained channel estimateor power measurement of the continuous time signal associated with thesymbol.

There may be scenarios when the symbol does not include anyinterference; this may be viewed as being a third category ofinterference. For example, in such instances, when the level of theinterference is categorized into a third category of the at least twocategorizes, the decoder directly decodes the symbol to make bestestimates of the at least one information bit contained therein. That isto say, no de-weighting of the symbol is performed in such instances;the symbol is passed directly through to the decoder for decodingprocessing.

The invention envisions any type of communication device that supportsthe functionality and/or processing described herein. Moreover, varioustypes of methods may be performed to support the functionality describedherein without departing from the scope and spirit of the invention aswell.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a diagram illustrating an embodiment of the frequencyspectrum of a UWB (Ultra Wide Band) signal when compared to some othersignal types according to the invention.

FIG. 1B is a diagram illustrating an embodiment of UWB (Ultra Wide Band)spectrum partitioning into a plurality of sub-bands according to theinvention.

FIG. 2A is a diagram illustrating an embodiment of a piconet or WPAN(Wireless Personal Area Network) (shown as a wireless communicationsystem) that is built according to the invention.

FIG. 2B is a diagram illustrating an embodiment of frequency hoppingthat may be performed according to the invention.

FIG. 3 is a diagram illustrating an embodiment showing comparison offrequency hopping time interval duration compared to a communicationchannel impulse response according to the invention.

FIG. 4 is a diagram illustrating another embodiment of frequency hoppingthat is performed according to the invention.

FIG. 5 is a diagram illustrating an embodiment of CDMA (Code DivisionMultiple Access) that may be employed according to the invention.

FIG. 6 is a diagram illustrating an embodiment of OFDM (OrthogonalFrequency Division Multiplexing) that may be employed according to theinvention.

FIG. 7 is a diagram illustrating an embodiment of SOPs (SimultaneouslyOperating Piconets) within relatively close proximity to one another(having some overlap) according to the invention.

FIG. 8 is a diagram illustrating another embodiment of SOPs withinrelatively close proximity to one another (having some overlap)according to the invention.

FIG. 9 is a diagram illustrating an embodiment of SOPs interferencecharacteristics according to the invention.

FIG. 10 is a diagram illustrating an embodiment of fast frequencyhopping with multipath and interference according to the invention.

FIG. 11 is a diagram illustrating an embodiment of SH-OFDM(Slow-Hopping-Orthogonal Frequency Division Multiplexing) according tothe invention.

FIG. 12 is a diagram illustrating an embodiment of reduced duty cycleSH-OFDM according to the invention.

FIG. 13 is a schematic block diagram illustrating a communication systemthat includes a plurality of base stations and/or access points, aplurality of wireless communication devices and a network hardwarecomponent in accordance with certain aspects of the invention.

FIG. 14 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device and an associatedradio in accordance with certain aspects of the invention.

FIG. 15 is a diagram illustrating an embodiment of a piconet operabledevice that supports functionality of interference compensationcapitalizing on structured interference according to the invention.

FIG. 16 is a diagram illustrating an embodiment of smart receiverstructure functionality that is built according to the invention.

FIG. 17A is a diagram illustrating an embodiment of functionality of asmart receiver according to the invention.

FIG. 17B is a diagram illustrating an embodiment of functionality ofinterference compensation capitalizing on structured interferenceaccording to the invention.

FIG. 18 is a diagram illustrating an embodiment of a 3^(rd) orderelliptical LPF (Low Pass Filter) employed at a transmitter and areceiver (or a transceiver) according to the invention.

FIG. 19 is a diagram illustrating another embodiment of a piconetoperable device that supports functionality of interference compensationcapitalizing on structured interference (showing PHY (physical layer),MAC (Medium Access Controller), and higher protocol layers) according tothe invention.

FIG. 20, FIG. 21, FIG. 22, and FIG. 23 are flowcharts illustratingvarious embodiments of methods for receive processing in a piconetoperable device according to the invention.

FIG. 24A, FIG. 24B, and FIG. 24C are flowcharts illustrating variousembodiments of methods for estimating a level (e.g., magnitude) ofinterference of a signal for use in performing interference compensationaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

A novel approach is presented herein by which a piconet, or SOPs(Simultaneously Operating Piconets), may operate in such a manner as tohave a minimal amount (if any) of interference between them. A singlecarrier (e.g., single carrier frequency) solution is provided in placeof an OFDM (Orthogonal Frequency Division Multiplexing) solution. Apiconet operable device is presented to include intelligence (e.g.,smart receiver structure within the piconet operable device) that isable to perform estimation of the location and level (e.g., magnitude)of the interference and to perform appropriate processing to minimizeits impact when demodulating and decoding a received signal. Forexample, this may involve selectively de-weighting only specific bits ofone or more individual symbols of the received and demodulated signal.

Some background information is initially provided below to acquaint thereader to the particular context of operation of piconet and their useof the UWB (Ultra Wide Band) portion of the frequency spectrum.

FIG. 1A is a diagram illustrating an embodiment of the frequencyspectrum of a UWB (Ultra Wide Band) signal when compared to some othersignal types according to the invention. In contradistinction to RF(Radio Frequency) communications that operate by using a narrowbandcarrier frequency to transmit information, UWB communications operate bysending pulses of energy across a broad frequency spectrum. For example,an RF signal may be viewed as occupying the range of spectra of anarrowband frequency. Also, in contradistinction to a spread-spectrumsignal whose intensity (magnitude) generally rises above the noise floorwithin an available spectrum and also occupies a relatively narrowerportion of the available spectrum, a UWB signal may actually be viewedas pulse shaped noise (that may never exceed the noise floor within theavailable spectrum). A spread-spectrum signal may be viewed as a signalthat occupies a frequency band that is much wider than the minimumbandwidth required by the information signal. For example, a transmitter“spreads” the energy (that is typically originally concentrated innarrowband) across a number of frequency band channels on a widerelectromagnetic spectrum. Some benefits of a spread-spectrum signalinclude improved privacy, decreased narrowband interference, andincreased signal capacity.

However, a UWB signal's PSD (Power Spectral Density) actually curvesacross the available spectrum, whereas the PSD of noise generally lookssimilar across the entire range of the available spectrum. Because ofthis distinction of shaping of the UWB signal and the noise across theavailable spectrum, the noise does not fully obliterate a pulse that istransmitted as a UWB signal. It is also important to note that a UWBsignal is a function of time, not frequency.

FIG. 1B is a diagram illustrating an embodiment of UWB (Ultra Wide Band)spectrum partitioning into a plurality of sub-bands (or channels)according to the invention. Relatively recently, the FCC (FederalCommunications Commission) has defined the available spectrum for UWBcommunications as being between 3.1 GHz (Giga-Hertz) and 10.6 GHz. Inaddition, the FCC defined the minimum spectral width of any sub-band (orchannel) within the available UWB spectrum to be 500 MHz (Mega-Hertz).

Moreover, this FCC definition allows for a PSD across the UWB spectrumof −41.25 dBm/MHz of bandwidth. As a brief review, 0 dBm is the dB(decibel) measure of power of a signal referenced to 1 mW (milli-Watt).This means that the total power that may be employed by a UWB signal isapproximately −14.26 dBm in any individual 500 MHz sub-band (or channel)within the entire available UWB bandwidth of 7.5 GHz. In addition, if apulse is sent using the entire 7.5 GHz of available UWB bandwidth, thenthe total power that may be employed by a UWB signal is approximately−2.5 dBm.

FIG. 2A is a diagram illustrating an embodiment of a piconet or WPAN(Wireless Personal Area Network) (shown as a wireless communicationsystem) that is built according to the invention. As described brieflyabove, a piconet may be viewed as being the network that is establishedwhen any two devices connect to support communication between them. Thisoperation is typically within the context of communication beingperformed in an M/S (Master/Slave) relationship. The piconet maytypically be implemented using a piconet controller (master) and 1 ormore user devices (slaves). The user devices (slaves) typically do notcommunication directly with one another in this embodiment, but witheach other through the piconet controller (master). However, 2 userdevices (slaves) may be set up by the piconet controller (master) tocommunicate directly with one another using p2p (peer to peer)communication. This p2p communication set up for the 2 user devices(slaves) is typically performed by the piconet controller (master).

To support communication between each of the plurality of user devices(slaves), simultaneously at some times, and the piconet controller(master), the communication must be implemented in such a way that thecommunication links between each user device (slave) and the piconetcontroller (master) do not interfere with the other communication linksbetween the other user devices (slaves) and the piconet controller(master). Moreover, when two or more piconets operate within relativelyclose proximity to one another, the communication within each of therespective piconets must be implemented in such a way thatsimultaneously operation of the two or more piconets (e.g., thecoexistence and operation) may be performed without interfering with oneanother.

While it is noted that the user devices (slaves) do not typicallycommunicate directly with one another (that is to say, via the piconetcontroller (master)), it is also noted that the piconet controller(master) may sometimes operate to enable p2p communication between the 2user devices (slaves) within the piconet. Moreover, the piconet in thisembodiment as well as within other embodiments described herein are alloperable in accordance with the conditions and constraints provided bythe IEEE (Institute of Electrical & Electronics Engineers) 802.15standard and may also be implemented such that the piconet is operablein accordance with other wireless communication standards as well.Moreover, this piconet is also operable within the various alternativeand subsequent drafts of the IEEE 801.15 standards being developedincluding the IEEE 802.15 WPAN High Rate Alternative PHY Task Group 3 a(TG3a) draft standard.

FIG. 2B is a diagram illustrating an embodiment of frequency hoppingthat is performed according to the invention. As a function of time, thefrequency band (or channel) that is being used will “hop” from onefrequency band (or channel) to another. Frequency hopping is one meansof operation that may be used to make a communication channel morerobust. For example, when noise, such as background noise, is relativelylocalized to a particular portion of the spectrum, the frequency hoppingwill help minimize the effects this frequency specific and frequencylocalized noise.

Frequency hopping may be viewed as a repeated switching of the frequencyof a signal during transmission. In a communication system, atransmitter and a receiver operate in synchronization so that eachoperates at the same frequency at any given time. In this particularembodiment, an available frequency spectrum is sub-divided into n bands(or n channels). The communication operates using a band 1 during afirst time interval, then operates using a band n during a second timeinterval, then operates using a band 3 during a third time interval, andso on as indicated in the diagram.

It is also noted that the time interval between the various frequencyhops may be implemented as being sufficiently long so as to permit thecapture of a communication channel's full impulse response at thevarious piconet operable devices within the piconet (e.g., the piconetcontroller (master) and the user devices (slaves)). This time intervalat which the communication system operates at any given frequency willtypically be multi-symbol lengths in duration. Alternatively, very fastfrequency hopping may be performed when such considerations are notdesired or critical.

As an example of the operation of frequency hopping, in the context of aUWB signal, the UWB spectrum may be divided into 15 sub-bands of 500 MHzbandwidth, the frequency hopping may be viewed as hopping between thevarious 500 MHz bandwidth sub-bands (or channels) as a function of time.

FIG. 3 is a diagram illustrating an embodiment showing comparison offrequency hopping time interval duration compared to a communicationchannel impulse response according to the invention. The impulseresponse, as a function of time, is shown for the communication channelbetween a user device (slave) and a piconet controller (master). Thisimpulse response may be viewed as the response of the communicationsystem when an impulse is provided thereto. The impulse response variesin intensity as a function of time before dissipating. The time that theimpulse response takes to dissipate completely may be viewed as theimpulse response time of the communication channel.

When compared to frequency hopping performed according to the invention,the time interval at which the communication system operates using afirst frequency band (shown as a band 1 during a first time interval) islonger than the impulse response time of the communication channel. Thiswill allow all of the energy of a pulse to be captured when transmittedand when operating at this frequency band. Similarly, when the operationswitches to another frequency band according to the frequency hoppingtime-frequency code sequence, that corresponding time interval will alsobe longer than the impulse response time of the communication channel.

Within some prior art piconet approaches, frequency hopping alone hasbeen implemented such that the time intervals are typically only of asingle symbol's length; this is typically much shorter than the impulseresponse time of the communication channel. Much of the energy of atransmitted pulse may be lost if the frequency hops are performed tooquickly. The longer duration over which the frequency hops are performedaccording to the invention allows for capturing of all of the energy ofthe transmitted pulse thereby ensuring more robust and more accuratecommunications. Alternatively, again, very fast frequency hopping may beperformed when such considerations are not desired or critical.

Within the context of the invention, the time-frequency code employed togovern communication between 2 devices within the piconet may be viewedas an operational parameter. This operational parameter may be modifiedin real time based on a change in another operational parameter thatgoverns communication between the 2 devices. For example, a 1^(st)time-frequency code may be employed at one time, and a 2^(nd)time-frequency code may be performed subsequently based on a change ofanother of the operational parameters. Based on a change in theoperational parameter of interference of the communication link between2 devices, as an example, one time-frequency code may more effectivelysupport communication between the 2 devices compared to the othertime-frequency codes that are available. As is also described in otherof the embodiments of the invention, other operational parameters mayalso be modified in response to a change in 1 or more of the otheroperational parameters as well without departing from the scope andspirit of the invention.

Again, as briefly mentioned above, it is also noted that the piconetcontroller (master) may enable p2p communication between two separateuser devices (slaves) within the piconet. The manner of communicationdescribed herein with respect to communication between the piconetcontroller (master) and any one user device (slave) is also applicableto p2p communication that may be performed between two separate userdevices (slaves) within the piconet.

FIG. 4 is a diagram illustrating another embodiment of frequency hoppingthat is performed according to the invention. The description of thisdiagram may be viewed as being a specific example of the operationalparameter of the time-frequency codes employed to support communicationacross various PHY (physical layer) links between the various deviceswithin the piconet.

This embodiment shows how two separate piconets (or two separate groupsof devices within a piconet) may operate using two separatetime-frequency codes that are orthogonal to one another. For example, afirst piconet (or first group of devices) performs frequency hopping forslave/master communication using a first time-frequency code(time-frequency code 1). In addition, a second piconet (or second groupof devices) performs frequency hopping for slave/master communicationusing a second time-frequency code (time-frequency code 1). During eachtime interval, the time-frequency code 1 and the time-frequency code 2each operate using a different band (or channel). For example, when thetime-frequency code 1 operates using the band 1, the time-frequency code2 operates using the band 2. Similarly, when the time-frequency code 1operates using the band 2, the time-frequency code 2 operates using theband 5. This orthogonal operation of the 2 time-frequency codescontinues for the duration of the respective time-frequency codesequences.

Each of the respective time-frequency code sequences are repeated tosupport subsequent operation of the respective piconets. This orthogonaloperation of employing two time-frequency codes allows more than onepiconet to coexist in relative close proximity with one another. Inaddition it is noted that all of the user devices (slaves) within arespective piconet (or group of devices) will communicate with theircorresponding piconet controller (master) using their time-frequencycode sequence, and all of the user devices (slaves) within anotherrespective piconet will communicate with their corresponding piconetcontroller (master) using their corresponding time-frequency codesequence.

FIG. 5 is a diagram illustrating an embodiment of CDMA (Code DivisionMultiple Access) that may be employed according to the invention. CDMAmay be viewed as the short term assignment of a frequency band tovarious signal sources. At each successive time slot, the bandassignments are reordered either adaptively or according to apredetermined sequence. For example, during a time slot 1, a signal 1operates using a band 1, a signal 2 operates using a band 2, and asignal 3 operates using a band 3. Then, during a time slot 2, the signal1 operates using the band 3, the signal 2 operates using the band 1, andthe signal 3 operates using the band 2. During a time slot 3, the signal1 operates using the band 1, the signal 2 operates using the band 2, andthe signal 3 operates using the band 3.

The operation of communication devices (e.g., users) is performed usinga PN (Pseudo-Noise) code that is typically orthogonal to the other PNscodes employed by the other communication devices within thecommunication system. This PN code is oftentimes referred to as aspreading code. A modulated signal is spread using that spreading codeand the spread signal is then transmitted across a communication channel(e.g., a PHY (physical layer) link that communicatively couples 2devices within the piconet). At a receiver end of the communicationchannel, this same spreading code (e.g., this PN code) is employed tode-spread the code so that data sent from a particular device may bedemodulated by the appropriate destination device.

The operation of CDMA may be better understood when viewed as thetransformation of an input signal through a communication system. At atransmitter end of a communication channel, input from a particular useris first provided to a modulator where the data is modulated by acarrier thereby generating a modulated signal (s1). Next, thedata-modulated signal is then multiplied by a spreading code (g1) thatcorresponds to that particular user thereby generating a spread signal(g1s1) that is then provided to the communication channel. This signalmay be viewed as a convolution of the frequency spectrum of themodulated signal and the frequency spectrum of the spreading code.Simultaneously, input from other users within the communication systemis modulated and spread in an analogous manner.

At the receiver end of the communication channel, a linear combinationof all of the spread signals provided by the other users is received,e.g., g1s1+g2s2+g3s3+ . . . and so on for all of the users. At thereceiver end, the total received signal is then multiplied by thespreading code (g1) thereby generating a signal that includes g1 ²s1plus a composite of the undesired signal (e.g., g1g2s2+g1g3s3+ . . . andso on).

In CDMA, the spreading codes are typically chosen such that they areorthogonal to one another. That is to say, when any one spreading codeis multiplied with another spreading code, the result is zero. This way,all of the undesired signals drop out. Given that the spreading codesg1(t), g2(t), g3(t) and so on, the orthogonality of the spreading codesmay be represented as follows:${\int_{0}^{T}{g\quad{i(t)}g\quad{j(t)}{\mathbb{d}t}}} = \left\{ \begin{matrix}{1,} & {i = j} \\{0,} & {i \neq j}\end{matrix} \right.$

This final signal is then passed to a demodulator where the input thathas been provided at the transmitter end of the communication channel isextracted and a best estimate is made thereof.

FIG. 6 is a diagram illustrating an embodiment of OFDM (OrthogonalFrequency Division Multiplexing) modulation that may be employedaccording to the invention. OFDM modulation may be viewed a dividing upan available spectrum into a plurality of narrowband sub-carriers (e.g.,lower data rate carriers). Typically, the frequency responses of thesesub-carriers are overlapping and orthogonal. Each sub-carrier may bemodulated using any of a variety of modulation coding techniques.

OFDM modulation operates by performing simultaneous transmission of alarger number of narrowband carriers (or multi-tones). Oftentimes aguard interval or guard space is also employed between the various OFDMsymbols to try to minimize the effects of ISI (Inter-SymbolInterference) that may be caused by the effects of multi-path within thecommunication system (which can be particularly of concern in wirelesscommunication systems). In addition, a CP (Cyclic Prefix) may also beemployed within the guard interval to allow switching time (when jumpingto a new band) and to help maintain orthogonality of the OFDM symbols.

In one UWB embodiment, 125 OFDM tones may be implemented in any one ofthe 15 sub-bands of 500 MHz bandwidth within the UWB spectrum. Otherbenefits are achieved using OFDM. For example, the use of multi-tonesallows for an effective solution to deal with narrowband interference.For example, a tone that corresponds to the locality of the narrowbandinterference may be turned off (to eliminate the susceptibility to thisnarrowband interference) and still provide for efficient operation. Thisturning off of these one or few tones will not result in a great loss ofbandwidth because each individual tone does not occupy a great deal ofbandwidth within the available spectrum employed by the OFDM symbol.Therefore, OFDM modulation provides a solution that may be employed inaccordance with invention that provides link quality intelligence fromthe PHY (physical layer) to the higher protocol layers within devicesoperating within wireless networks (e.g., piconets as one example).

FIG. 7 is a diagram illustrating an embodiment of SOPs (SimultaneouslyOperating Piconets) within relatively close proximity to one another(having some overlap) according to the invention. This embodiment showshow various piconets may operate in such a way that the individualdevices within these piconets are sufficiently close to one another thatthey may sometimes even associate with different piconets at differenttimes. This inherently requires operating the various piconets in such away that they do not interfere with one another. For example, eachpiconet may operate using a different frequency hopping approach. Eachpiconet may employ a different time-frequency code such that undesirablesymbol collisions are kept at a relatively low rate of occurrence. Otheroperational parameters may alternatively be employed for each of thevarious piconets. For example, different PN (Pseudo-Noise) codes may beemployed to govern the spreading/de-spreading of symbols transmittedwithin the various piconets. Moreover, even other operational parametersmay be implemented such that any undesirable symbol collisions at keptat a relative minimum.

The manner in which the various devices within the piconet operate maybe performed in such a way that when symbol collisions do in fact occur(e.g., when interference does occur) the interference has a particularcharacteristic, namely, a relatively structured interference.Thereafter, using an understanding of this structured interference,intelligent processing of symbols within the various devices may be madeso as to support a much higher level of performance than is provided bycommunication systems whose high end of performance is limited by theAWGN (Additive White Gaussian Noise) existent within the communicationsystem. The performance of a piconet operating this way will typicallybe limited only by the out of band roll off and front end range (e.g.,the radio front end and the filtering performed therein) of a deviceoperating within such a piconet.

Various aspects of the invention operate the various devices within apiconet using a combination of SH-OFDM (Slow Hopping-OrthogonalFrequency Division Multiplexing) and a relatively slower PRF (PulseRepetition Frequency) than is typically performed within prior artpiconets. By operating the various devices of the piconet in such a way,when symbol collisions do in fact occur, they will exhibit thestructured interference briefly describe above. Several examples areprovided below showing more particularly how symbol collisions willexhibit this structured interference. In addition, various embodimentsare also described about how this structure interference may becapitalized upon to ensure a high level of performance of the overallpiconet.

As shown within this embodiment, a piconet A includes a piconetcontroller A (master) and user devices 1A & 2A (slaves). Similarly, apiconet C includes a piconet controller C (master) and user devices 1C &2C (slaves). In addition, a piconet B includes a piconet controller B(master) and a user device 1B (slave).

As can be seen, each of these various piconets A, B, and C operate suchthat they may have a portion of overlap with 1 or more of the otherpiconets. Some of the devices within these piconets may associate withdifferent piconets at different points in time.

Again, each of the various devices within the piconets A, B, and C mayoperate using individually selected time-frequency codes that includeappropriate combinations of SH-OFDM and a relatively slower PRFs thanare typically performed within prior art piconets. By operating thepiconets A, B, and C in such a manner that when symbol collisions in theregion, they exhibit a relatively structured type of interference.Having an understanding of the nature of this structured interferenceallows the implementation of a receiver having some intelligence thatmay appropriately de-weight symbols that have experienced an undesirablesymbol collision.

FIG. 8 is a diagram illustrating another embodiment of SOPs withinrelatively close proximity to one another (having some overlap)according to the invention. However, in contradistinction to theembodiment described above, this embodiment shows how differenttime-frequency codes may be implemented even within a given piconet.This may be performed in addition to (e.g., in conjunction with) thedifferent time-frequency codes being implemented for different piconets.

This embodiment shows a number of user devices (slaves) and 2 piconetcontrollers (masters) within a region. If desired, the locations of thevarious devices within this region may be ascertained using any numberof means. In one such embodiment, both of the piconet controllers 1 & 2(masters) are operable to perform ranging of all of the user devices(slaves) within the region. Together, the piconet controller (master) 1and the piconet controller (master) 2 perform this ranging of all of theuser devices (slaves), group them accordingly, an also select theappropriate time-frequency codes that are used to govern thecommunication between the user devices (slaves) and the piconetcontrollers 1 & 2 (masters). In addition, one or both of the piconetcontrollers 1 & 2 (masters) may also direct 2 or more of the userdevices (slaves) to perform p2p communication between them and performranging of the relative distances between them; this information maythen be provided to both of the piconet controllers 1 & 2 (masters). Indoing so, triangulation may be performed by one or both of the piconetcontrollers 1 & 2 (masters) to determine the precise location of theuser devices (slaves) within the region.

The distribution of the user devices (slaves) in this embodiment is suchthat the user devices (slaves) may appropriately be grouped to operatewith one particular piconet controller (master) within the region. Forexample, those user devices (slaves) closer in vicinity to the piconetcontroller 2 (master) may be grouped within one group; that is to say,user devices 2, 3, & 6 (slaves) may be grouped within a zone whosecommunication is governed according to one time-frequency code in onepiconet (e.g., piconet 2).

Similarly, the piconet controller 1 (master) services the other userdevices 1 & 4 (slaves) (within a zone 1 using another time-frequencycode), and the piconet controller 1 (master) services user device 5(slave) (as being outside a zone 3 using yet another time-frequencycode). These user devices (slaves) and the piconet controller 1 (master)may be viewed as being another piconet (e.g., piconet 1).

Alternatively, the communication between the various groups of userdevices (slaves) and their respective piconet controller (master) may begoverned using different profiles. Each of these profiles may includeinformation corresponding to the time-frequency code employed, the rateof frequency hopping, and/or the PRF that governs the communication ofthose devices (among other operational parameters). Generally speaking,this embodiment shows how the communication between various devices maynot only be implemented differently within different piconets, but alsomay be implemented differently between various devices within a givenpiconet.

FIG. 9 is a diagram illustrating an embodiment of SOPs interferencecharacteristics according to the invention. The interference regions areshown in this diagram for many different ways of implementing SOPs. Aspectrum of lowest capacity of a piconet communication system ranging toa highest capacity is shown for various manners in which a piconetcommunication system may be operated. At the lowest capacity end of thespectrum, the interference is perfectly correlated. At the highestcapacity end of the spectrum, the interference is perfectly orthogonal.In the interim, there is a region of the spectrum where the interferenceis perfectly de-correlated. This region may be characterized asunstructured interference. Moving towards the highest capacity portionof the spectrum, there is a portion of the spectrum where theinterference may then be characterized as structured interference.

Starting at the low end of capacity, correlated interference may becharacterized as interference that looks similar to the desired signal.To accommodate this type of interference, a matched filter (rake) may beimplemented to coherently sum the desired signal. However, such amatched filter (rake) also coherently sums the undesired signal as wellas the desired signal, and this typically requires more complex receiverprocessing. No spreading gain is realized in this type of situation. Inpractice, multipath typically tends to de-correlate interference, thoughit is not guaranteed.

Continuing up the spectrum towards the highest capacity end,White-noise-like interference may be characterized as interference thatlooks like WGN (White Gaussian Noise). A matched filter (rake) may beimplemented that coherently sums the desired signal, while theinterference is summed incoherently. For this type of interference,spreading gain is in fact realized. There are a variety of techniques inwhich this may be implemented. For example, different code sets may beimplemented for different piconets. Alternatively, long PN(Pseudo-Noise) sequences (or short PN sequences) may be implemented.Time-hopping may alternatively be performed. In addition, baud/chip-rateoffsets may be employed as well.

Within the context of structured interference, fast or slow frequencyhopping may be performed. One embodiment of the invention includesemploying combined SH-OFDM (Slow Hopping-Orthogonal Frequency DivisionMultiplexing) that inherently provides a structured type of interferencethat may be handled very effectively using a receiver with some embeddedintelligence to accommodate any undesirable symbol collisions. One ofthe reasons that this structure type of interference offers benefitsover the WGN (White Gaussian Noise) is that this type of structuredinterference has lower entropy than interference added via AWGN(Additive White Gaussian Noise). This lower entropy may be deduced whenanalyzing and comparing these types of interferences. One example thatmay be implemented to achieve this structured interference is frequencyhopping (or time-frequency interleaving), with coding acrossfrequencies. The interference level then varies with time and frequency.Well-designed receivers can exceed the nominal spreading gain that maybe achieved using prior art receivers. In addition some techniques inwhich this may be achieved include using reliability metrics in aViterbi decoder (e.g., a smart receiver having some embeddedintelligence). Alternatively, a non-linear limiter may be implemented ina receive path (e.g., in a dumb receiver).

Moving to the right hand portion of the spectrum, orthogonalinterference may be found that is perfectly orthogonal. Examples ofmeans of operating a communication system to achieve this orthogonalinterference FDM (Frequency Division Multiplexing) that does, however,incur a transmit power penalty. In addition, any truly orthogonal codedoes require synchronization for proper performance. The advantage ofsuch orthogonal codes is that there exists no theoretical limit to theinterference distance of interference that is generated by such codes.

FIG. 10 is a diagram illustrating an embodiment of fast frequencyhopping with multipath and interference according to the invention. Thisembodiment shows various time-frequency codes implemented within variouspiconets may suffer symbol collisions.

At the top of the diagram, free space communication of pulses is shown.As can be seen, 1 symbol “collision” will occur per cycle (if thetime-frequency codes are synchronized with one another. This solutiondoes provide good immunity to the near-far problem, and a single RF(Radio Frequency) front end may be implemented such that it captures allof the energy of the received pulses.

In the middle of the diagram, CM1 channels are shown where theinterference is smeared over several pulses (and not uniformly).Unfortunately, this implementation presents less immunity to thenear-far problem. Also unfortunately, a single RF (Radio Frequency)front end cannot capture all of the energy of received symbols.

At the bottom of the diagram, CM2 channels are shown where theinterference starts to look like WGN (White Gaussian Noise). Thisinterference behaves more similar to that of a wideband system.Therefore, to accommodate such signaling, a wideband front end need beimplemented.

These various types of interference, generated by SOPs show more clearlyand how difficult effective receiver processing may be when trying todeal with interference that does not have a predictable and manageablestructure. Various aspects of the invention show how structure (andtherefore more manageable) interference may be generated by operatingvarious SOPs in a particular manner. For example, when operating theseSOPs using SH-OFDM (Slow Hopping-Orthogonal Frequency DivisionMultiplexing) combined with a reduced PRF (Pulse Repetition Frequency),when compared to prior art piconets, will allow for the intelligentmanaging symbol collisions.

The current proposal for Multi-Band OFDM (MB-OFDM), shown as references[1,2] below, for IEEE 802.15.3a suffers from poor performance in thepresence of close SOPs (Simultaneously Operating Piconets).

The Internet URLs for the above references documents are provided here:

-   -   [1]        http://grouper.ieee.org/groups/802/15/pub/2003/Jul03/03267r5P802-15_TG3a-Multi-band-OFDM-CFP-Presentation.ppt    -   [2]        http://grouper.ieee.org/groups/802/15/pub/2003/Jul03/03268r0P802-15_TG3a-Multi-band-CFP-Document.doc

Theoretically, a Multi-Band (time-hopping) system can achieve muchbetter performance than a wideband (CDMA (Code Division MultipleAccess)) system by exploiting the structured nature of the interference,but the current proposal fails to do this. In fact, it does not achieveeven the nominal interference suppression of a wideband CDMA system.

FIG. 11 is a diagram illustrating an embodiment of SH-OFDM(Slow-Hopping-Orthogonal Frequency Division Multiplexing) according tothe invention. Two (2) separate piconets (e.g., a piconet 1 and apiconet 2) each operate using different time-frequency codes, as can beseen where the frequency bands employed are changed as a function oftime. During some instances, a common frequency band is employed by bothpiconets and undesirable symbol collisions may occur. One such effect isthat, when a symbol collision occurs, the energy of such a “symbol”(really a symbol-(collision-modified-symbol) will incur a greater amountof energy (or power).

However, one advantage of operating in such a way is that theinterference in actually highly structured. This is true even in thepresence of multipath effects within the piconets. There is a drawback,however, in that, unfortunately, for a 3 band system with 1 interferer,a receiver will typically see 2 collisions per 3 symbols. To compensatefor this, the piconet may require a very low rate code to work at a highISR (Interference to Signal Ratio). Moreover, the piconet may notachieve the target rates at the high ISR.

This diagram illustrates 2 adjacent piconets in a 3-band system, wherethe two piconets use different time-frequency codes. As shown, thistypically results in 2 partial collisions out of every 3 symbols.Unfortunately, although the partial collisions affect only a portion ofeach hop in the time-domain, they affect all tones in the frequencydomain. Thus, in an OFDM system, all bits are affected by a partialcollision. In situations where the interferer is much closer than thetransmitter of the desired signal, these collisions will be treated aserasures, and 2 out of every 3 coded bits will be erased.

However, the fact that the interference is highly structure, even in thepresence of multipath, does provide for some operational advantages. Inaccordance with the SH-OFDM, by dwelling longer on each frequency band,symbol collisions may be confined to a single frequency hop. However,dealing with 2 partial collisions out of every 3 symbols can beextremely problematic for many applications.

FIG. 12 is a diagram illustrating an embodiment of reduced duty cycleSH-OFDM according to the invention. This diagram shows an alternativeembodiment where the number of information bits is increased per symbolthereby eliminating the conjugate symmetry; then the symbol rate isreduced. In other words, the power level of each symbol and the numberof bits per tone in increased, and the rate at which symbols are sent isdecreased (alternatively, the symbol rate may be decreased). Asillustrated in this diagram, this reduces the collision rate by a factorof 2, so that at most 1 out of every 3 coded bits will be erased (versus2 out 3 in the embodiment described above).

This reduced duty cycle MB-OFDM (Multi-band Orthogonal FrequencyDivision Multiplexing) approach described with respect to this diagramwas initially introduced in another pending patent application (AttorneyDocket No. BP3085, filed Jul. 18, 2003 (Jul. 18, 2003), pending), andlater introduced within a proposal made by the inventor [3].

The Internet URL for the above referenced document is provided here:

-   -   [3]        http://grouper.ieee.org/groups/802/15/pub/2003/Jul03/03273r0P802-15_TG3a-Reduced-Duty-Cycle-MB-OFDM.ppt

This diagram shows an alternative embodiment where the number ofinformation bits is increased per symbol thereby eliminating theconjugate symmetry; then, the symbol rate is reduced.

Again, as with the embodiment shown above, two (2) separate piconets(e.g., a piconet 1 and a piconet 2) each operate using differenttime-frequency codes, as can be seen where the frequency bands employedare changed as a function of time. During some instances, a commonfrequency band is employed by both piconets and undesirable symbolcollisions may occur. One such effect is that, when a symbol collisionoccurs, the energy of such a “symbol” (really asymbol-collision-modified-symbol) will incur a greater amount of energy(or power).

Within such an embodiment, a 3 band system will see at most 1 collisionper 3 symbols. This is a large improvement over the 2 collisions per 3symbols as shown within the above embodiment.

Some of the advantages of such a system, implemented using well designedcodes, include the fact that such a system can reach the target rateseven at high ISR (Interference to Signal Ratio). In addition, there isbonus of such a system, in that, reduced power consumption may besupported at the receiver. The receiver can turn off its radio andanalog front end during silence periods.

However, such a system may be viewed as having some disadvantages. Forexample, some of the disadvantages of such a system may be characterizedto include a 3 dB PAR (Peak to Average Power Ratio) limitation. Inaddition, there is lost diversity on the frequency selective channels,and the implementation of such a system requires 2 separate DACs(Digital to Analog Converters). Moreover, this scheme suffers from 3perhaps more significant drawbacks.

1. It gives up frequency diversity over fading channels, which resultsin a penalty of about 1 dB (decibels) at 110 Mbps (Mega-bits persecond), and more at higher rates.

2. It increases the peak transmitted power by 3 dB, which may require amore expensive transmitter.

3. Most importantly, it only works if all piconets within the vicinityoperate in this mode. Thus, it requires some mechanism to enforce theuse of this mode when close SOPs are present.

While the advantages of such a system nevertheless do provide anadvantage over the prior art, an even improved new mode of operates ispresented herein that achieves the goals of reduced duty-cycle MB-OFDMbut doesn't suffer from the above-described shortcomings.

A novel proposed solution consists of transmitting a single-carriersignal in place of the OFDM signal and also implementing a piconetoperable device to include smart receiver structure functionality thatis capable of estimating the interference power per bit and de-weightingthe input to the Viterbi decoder accordingly. This may be viewed asbeing an additional mode of operation in an MB-OFDM system that may alsoemploy the same hopping pattern and the same RF architecture.

Referring to FIG. 11, it can be seen that the partial collisions affectonly a portion of each signal (e.g., not the entirety of the signal butonly a portion). In this proposed mode of operation using the singlecarrier, the bits are transmitted in the time domain, so that the onlybits affected by collisions are those corresponding to the portion ofthe signal experiencing the collision. This is a fundamental advantageto using the single carrier approach over using an OFDM approach, wherethe collisions are undesirably spread across all bits in thefrequency-domain.

The proposed solution dramatically improves performance in the presenceof close SOPs, without sacrificing frequency diversity, withoutincreasing the peak transmitted power, and without requiring otherpiconets to use this mode. In addition, it offers a simple low-powertransmission mode suitable for applications where the power of thetransmitter must be minimized.

Certain operational characteristics of a transmitter-capable device(e.g., generically a piconet operable device) that is compatible with areceiver-capable device (e.g., again, another generically a piconetoperable device) may be described below.

There are several possible good choices of operational parameters thatmay be selected for such a system that is built in accordance with theinvention. Some of these are described here. The current MB-OFDMproposal uses an IFFT (Inverse Fast Fourier Transform) output samplingrate of 528 MHz. For synergy with the MB-OFDM components, it is easiestto use a symbol rate which is an integer fraction of the IFFT outputsampling rate.

As such, one good choice of parameters would be as follows:

-   -   Symbol Rate=528/3=176 MHz (Mega-Hertz).    -   QPSK (Quadrature Phase Shift Key) modulation.    -   Rate ⅓ convolutional code: G=[117 155 127].    -   Data rate=176 MHz*⅔=117.33 MHz.

Because this symbol rate is less than {fraction (1/2)} the bandwidth ofthe transmitted signal, it results in a frequency-diverse signal (asdescribed in another patent having common inventorship as the presentpatent application). In other words, the same information is transmittedindependently in at least 2 frequency bands spaced 176 MHz apart. Thisspacing is larger than the coherence bandwidth of the channel, so thetwo spectral regions experience independent fading.

The interleaver would be designed such that each output from theconvolutional encoder is mapped to a different sub-band. This code waschosen such that if any one output stream is punctured, the resultingrate ½ code is still a strong code.

Moreover, there are several other useful choices of parameters. For anyset of parameters, it is critical to design the code and the interleaversuch that the code remains a strong code in the presence of erasuresthat any possible collision pattern can cause.

The following diagram is provided to show one type of a generic wirelesscommunication system embodiment in which aspects of the invention may befound.

FIG. 13 is a schematic block diagram illustrating a communication systemthat includes a plurality of base stations and/or access points, aplurality of wireless communication devices and a network hardwarecomponent in accordance with certain aspects of the invention. Thewireless communication devices may be laptop host computers, PDA(Personal Digital Assistant) hosts, PC (Personal Computer) hosts and/orcellular telephone hosts. The details of any one of these wirelesscommunication devices is described in greater detail with reference toFIG. 14 below.

The BSs (Base Stations) or APs (Access Points) are operably coupled tothe network hardware via the respective LAN (Local Area Network)connections. The network hardware, which may be a router, switch,bridge, modem, system controller, et cetera, provides a WAN (Wide AreaNetwork) connection for the communication system. Each of the BSs or APshas an associated antenna or antenna array to communicate with thewireless communication devices in its area. Typically, the wirelesscommunication devices register with a particular BS or AP to receiveservices from the communication system. For direct connections (i.e.,point-to-point communications), wireless communication devicescommunicate directly via an allocated channel.

Typically, BSs are used for cellular telephone systems and like-typesystems, while APs are used for in-home or in-building wirelessnetworks. Regardless of the particular type of communication system,each wireless communication device includes a built-in radio and/or iscoupled to a radio. The radio includes a highly linear amplifier and/orprogrammable multi-stage amplifier as disclosed herein to enhanceperformance, reduce costs, reduce size, and/or enhance broadbandapplications.

FIG. 14 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device and an associatedradio in accordance with certain aspects of the invention. For cellulartelephone hosts, the radio is a built-in component. For PDA (PersonalDigital Assistant) hosts, laptop hosts, and/or personal computer hosts,the radio may be built-in or an externally coupled component.

As illustrated, the host device includes a processing module, memory,radio interface, input interface and output interface. The processingmodule and memory execute the corresponding instructions that aretypically done by the host device. For example, for a cellular telephonehost device, the processing module performs the correspondingcommunication functions in accordance with a particular cellulartelephone standard or protocol.

The radio interface allows data to be received from and sent to theradio. For data received from the radio (e.g., inbound data), the radiointerface provides the data to the processing module for furtherprocessing and/or routing to the output interface. The output interfaceprovides connectivity to an output display device such as a display,monitor, speakers, et cetera, such that the received data may bedisplayed or appropriately used. The radio interface also provides datafrom the processing module to the radio. The processing module mayreceive the outbound data from an input device such as a keyboard,keypad, microphone, et cetera, via the input interface or generate thedata itself. For data received via the input interface, the processingmodule may perform a corresponding host function on the data and/orroute it to the radio via the radio interface.

The radio includes a host interface, a digital receiver processingmodule, an ADC (Analog to Digital Converter), a filtering/gain module,an IF (Intermediate Frequency) mixing down conversion stage, a receiverfilter, an LNA (Low Noise Amplifier), a transmitter/receiver switch, alocal oscillation module, memory, a digital transmitter processingmodule, a DAC (Digital to Analog Converter), a filtering/gain module, anIF mixing up conversion stage, a PA (Power Amplifier), a transmitterfilter module, and an antenna. The antenna may be a single antenna thatis shared by the transmit and the receive paths as regulated by theTx/Rx (Transmit/Receive) switch, or may include separate antennas forthe transmit path and receive path. The antenna implementation willdepend on the particular standard to which the wireless communicationdevice is compliant.

The digital receiver processing module and the digital transmitterprocessing module, in combination with operational instructions storedin memory, execute digital receiver functions and digital transmitterfunctions, respectively. The digital receiver functions include, but arenot limited to, digital IF (Intermediate Frequency) to basebandconversion, demodulation, constellation de-mapping, decoding, and/ordescrambling. The digital transmitter functions include, but are notlimited to, scrambling, encoding, constellation mapping, modulation,and/or digital baseband to IF conversion. The digital receiver andtransmitter processing modules may be implemented using a sharedprocessing device, individual processing devices, or a plurality ofprocessing devices. Such a processing device may be a microprocessor,micro-controller, DSP (Digital Signal Processor), microcomputer, CPU(Central Processing Unit), FPGA (Field Programmable Gate Array),programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on operational instructions. The memorymay be a single memory device or a plurality of memory devices. Such amemory device may be a ROM (Read Only Memory), RAM (Random AccessMemory), volatile memory, non-volatile memory, static memory, dynamicmemory, flash memory, and/or any device that stores digital information.It is noted that when either of the digital receiver processing moduleor the digital transmitter processing module implements one or more ofits functions via a state machine, analog circuitry, digital circuitry,and/or logic circuitry, the memory storing the corresponding operationalinstructions is embedded with the circuitry comprising the statemachine, analog circuitry, digital circuitry, and/or logic circuitry.

In operation, the radio receives outbound data from the host device viathe host interface. The host interface routes the outbound data to thedigital transmitter processing module, which processes the outbound datain accordance with a particular wireless communication standard (e.g.,IEEE 802.11, Bluetooth®, et cetera) to produce digital transmissionformatted data. The digital transmission formatted data is a digitalbase-band signal or a digital low IF signal, where the low IF typicallywill be in the frequency range of one hundred kHz (kilo-Hertz) to a fewMHz (Mega-Hertz).

The DAC converts the digital transmission formatted data from thedigital domain to the analog domain. The filtering/gain module filtersand/or adjusts the gain of the analog signal prior to providing it tothe IF mixing stage. The IF mixing stage converts the analog baseband orlow IF signal into an RF signal based on a transmitter local oscillationprovided by local oscillation module. The PA amplifies the RF signal toproduce outbound RF signal, which is filtered by the transmitter filtermodule. The antenna transmits the outbound RF signal to a targeteddevice such as a base station, an access point and/or another wirelesscommunication device.

The radio also receives an inbound RF signal via the antenna, which wastransmitted by a BS, an AP, or another wireless communication device.The antenna provides the inbound RF signal to the receiver filter modulevia the Tx/Rx switch, where the Rx filter bandpass filters the inboundRF signal. The Rx filter provides the filtered RF signal to the LNA,which amplifies the signal to produce an amplified inbound RF signal.The LNA provides the amplified inbound RF signal to the IF mixingmodule, which directly converts the amplified inbound RF signal into aninbound low IF signal or baseband signal based on a receiver localoscillation provided by local oscillation module. The down conversionmodule provides the inbound low IF signal or baseband signal to thefiltering/gain module. The filtering/gain module filters and/or gainsthe inbound low IF signal or the inbound baseband signal to produce afiltered inbound signal.

The ADC converts the filtered inbound signal from the analog domain tothe digital domain to produce digital reception formatted data. In otherwords, the ADC samples the incoming continuous time signal therebygenerating a discrete time signal (e.g., the digital reception formatteddata). The digital receiver processing module decodes, descrambles,demaps, and/or demodulates the digital reception formatted data torecapture inbound data in accordance with the particular wirelesscommunication standard being implemented by radio. The host interfaceprovides the recaptured inbound data to the host device via the radiointerface.

As one of average skill in the art will appreciate, the wirelesscommunication device of FIG. 14 may be implemented using one or moreintegrated circuits. For example, the host device may be implemented onone integrated circuit, the digital receiver processing module, thedigital transmitter processing module and memory may be implemented on asecond integrated circuit, and the remaining components of the radio,less the antenna, may be implemented on a third integrated circuit. Asan alternate example, the radio may be implemented on a singleintegrated circuit. As yet another example, the processing module of thehost device and the digital receiver and transmitter processing modulesmay be a common processing device implemented on a single integratedcircuit. Further, the memories of the host device and the radio may alsobe implemented on a single integrated circuit and/or on the sameintegrated circuit as the common processing modules of processing moduleof the host device and the digital receiver and transmitter processingmodule of the radio.

FIG. 15 is a diagram illustrating an embodiment of a piconet operabledevice that supports functionality of interference compensationaccording to the invention.

This embodiment of a piconet operable device includes an antenna that isoperable to communicate with any 1 or more other piconet operabledevices within the piconet. An antenna interface communicatively couplesa signal to be transmitted from the piconet operable device or a signalreceived by the piconet operable device to the appropriate path (be itthe transmit path or the receive path).

A radio front end includes receiver functionality and transmitterfunctionality. The radio front end communicatively couples to ananalog/digital conversion functional block. The radio front endcommunicatively couples to a modulator/demodulator, and the radio frontend communicatively couples to a channel encoder/decoder.

Along the Receive Path:

The receiver functionality of the front end includes a LNA (Low NoiseAmplifier)/filter. The filtering performed in this receiverfunctionality may be viewed as the filtering that is limiting to theperformance of the device, as also described above. The receiverfunctionality of the front end performs any down-converting that may berequiring (which may alternatively include down-converting directingfrom the received signal to a baseband signal). This front end may beviewed as receiving a continuous time signal, and performing appropriatefiltering and any down conversion necessary to generate the basebandsignal. Whichever manner of down conversion is employed, a basebandsignal is output from the receiver functionality of the front end andprovided to an ADC (Analog to Digital Converter) that samples thebaseband signal (which is also a continuous time signal, though at thebaseband frequency) and generates a discrete time signal baseband signal(e.g., a digital format of the baseband signal); the ADC also outputsthe digital I, Q (In-phase, Quadrature) components of the discrete timesignal baseband signal.

These I, Q components are provided to a demodulator portion of themodulator/demodulator where any modulation decoding/symbol mapping isperformed where the I, Q components of the discrete time signal basebandsignal. The appropriate I, Q components are then mapped to anappropriate modulation (that includes a constellation and correspondingmapping). Examples of such modulations may include BPSK (Binary PhaseShift Key), QPSK (Quadrature Phase Shift Key), 8 PSK (8 Phase ShiftKey), 16 QAM (16 Quadrature Amplitude Modulation), and even higher ordermodulation types. In this demodulator portion of themodulator/demodulator, embedded intelligence is included to support thefunctionality of the interference compensation described within other ofthe various embodiments. For example, this may include selectivelyde-weighting those symbols that have undergone a symbol collision. Thisinterference compensation may be performed by capitalizing in theinherent properties of the structured interference supported byoperating the piconet in a manner according to the invention. This mayalso involve treating certain interference affected bits as erasures andappropriately de-weighting other interference affected bits. Theseselectively modified symbols are then provided to a decoder portion ofthe channel encoder/decoder where best estimates of the information bitscontained within the received symbols are made.

Along the Transmit Path:

Somewhat analogous and opposite processing is performed in the transmitpath when compared to the receive path. Information bits that are to betransmitted are encoded using an encoder of the channel encoder/decoder.These encoded bits are provided to a modulator of themodulator/demodulator where modulation encoding/symbol mapping may beperformed according to the modulation of interest. These now I, Qcomponents of the symbols are then passed to a DAC (Digital to AnalogConverter) of the analog/digital conversion functional block totransform the I, Q components into a continuous time transmit signal(e.g., an analog signal). The now continuous time transmit signal to betransmitted is then passed to a transmit driver that performs anynecessary up-converting/modification to the analog signal (e.g.,amplification and/or filtering) to comport it to the communicationchannel over which the signal is to be transmitted to another piconetoperable device via the antenna.

FIG. 16 is a diagram illustrating an embodiment of smart receiverstructure functionality that is built according to the invention. Thisdiagram describes a structure of a smart receiver that may effectuatemany of the various aspects of the invention. It is noted that thissmart receiver structure functionality may be found within any piconetoperable device described herein including various transceivers andreceivers.

The front end portion of the smart receiver structure functionalityreceives an input that is a continuous time signal. This received smartreceiver structure functionality performs the appropriate mixing using afrequency hopping mixer that uses the same frequency hopping approachused to generate the signal at the transmit end of the communicationchannel. For example, this may be a educed duty cycle SH-OFDM approachas described above on an alternative embodiment. This appropriatelymixed version of the received continuous time signal is provided to anADC (Analog to Digital Converter) that samples the received continuoustime signal thereby generating a discrete time signal. The ADC may alsobe implemented to extract the I, Q components of the discrete timesignal as well. These I, Q components of the discrete time signal areprovided to a demodulator. The demodulator may be implemented usingvarious digital signal processing techniques. The demodulator employsthe appropriate functionality to perform selective de-weighting based onthe location and magnitude of the level (e.g., magnitude) ofinterference that the received signal may have experienced when beingtransmitted from a transmitting piconet operable device to a receivingpiconet operable device including this smart receiver structurefunctionality.

The demodulator also includes functionality to support afractionally-spaced linear equalizer that is operable to sum over thevarious spectral regions of a frequency-diverse signal that may havebeen transmitted from a transmitting piconet operable device. Thedemodulator also includes various functionality to perform theappropriate estimation and location of the level (e.g., magnitude) ofcollisions that may have occurred to the received signal. In otherwords, the smart receiver structure functionality is operable tocharacterize the level of the interference so that different types ofinterference may be dealt with differently and appropriately.

This diagram shows a very general, simplified example of the smartreceiver structure functionality that is capable to support variousaspects of the invention. This diagram illustrates how the input to theViterbi decoder is de-weighted based on the estimated interferencelevel. For very high-level interference (e.g., a first level ofinterference), it is sufficient to treat the affected bits as erasures,but for medium-level interference (e.g., a second level ofinterference), it is better to de-weight the input to the Viterbidecoder based on the magnitude of the interference.

Specifically, for optimal decoding, the LLR (log-likelihood ratio) inputto the Viterbi decoder is de-weighted by multiplying the LLR by theinverse of the square of the RMS (Root Mean Square) interference level.In this illustrated embodiment, the interference level is estimated atthe receiver by measuring the total instantaneous signal power,averaging the signal power, and subtracting the expected referencesignal power based on the previously-obtained channel estimate orreference signal power measurement. This is shown as being all performedwithin the demodulator. There are many possible variations on theapproach to estimate the interference power level. For one example,instead of using the average signal power that is determined directly,an alternatively embodiment of the smart receiver structurefunctionality may exploit predetermined knowledge of the inherentstructure of the interference (in the SOPs (Simultaneously OperatingPiconets) context). For another example, the smart receiver structurefunctionality could estimate the starting and ending points of theinterference and adjust the de-weighting factor accordingly.

In addition, there are several possible equalizer structures that may beimplemented in accordance with the invention (e.g., besides thefractionally-spaced linear equalizer that is illustrated). Forfrequency-diverse modes of operation (e.g. a transmitted signalincluding the same information transmitted independently over more thanone frequency band), a good choice is a fractionally-spaced linearequalizer. A fractionally-spaced equalizer can optimally sum the variousspectral regions of the frequency-diverse signal to allows theappropriate subsequent processing thereof.

FIG. 17A is a diagram illustrating an embodiment of functionality of asmart receiver according to the invention. It is noted that thisfunctionality of a smart receiver may be included within any type ofpiconet operable device that can perform receiver processing includingreceiver and transceiver type devices. This diagram illustratesgenerally how an input signal undergoes interference estimation andbased on that interference estimate, the input signal may be modifiedaccordingly. For example, the interference may be categorized into atleast 2 different types based on the level of the interference (or 3different types if one considers that little or no interference is a3^(rd) category).

The input to the decoder is selectively de-weighted based on the levelof the estimated interference. For a very high-level of interference(e.g., a first level of interference), it is sufficient to treat theaffected bits as erasures. However, for a medium-level of interference(e.g., a second level of interference), it is better to de-weight theinput to the decoder based on the magnitude of the interference.

In addition, if one considers that little or no interference is a 3^(rd)category (e.g., a third level of interference or no interference), thenfor little or no interference, no de-weighting would be performed on theinput to the decoder.

FIG. 17B is a diagram illustrating an embodiment of functionality ofinterference compensation capitalizing on structured interferenceaccording to the invention. This capitalizing may be viewed as being amanner in which receiver processing may be employed is performed in sucha way as to operate in an intelligent manner using the intrinsiccharacteristics and nature of the structured type of interference thatmay be existent in the received signal. This may be viewed as beingperformed in such a way that a demodulator, within a communicationdevice, selectively performs interference compensation of a symbol byselectively de-weighting the symbol based on structured interferenceexistent therein. This selective de-weighting of the symbol may includeperforming no de-weighting in some instances while performing somede-weighting in other instances.

In this embodiment, one or more symbols are received by thisfunctionality. A symbol energy detection functional block is operable toperform detection of the energy of received symbols.

After the symbol energy detection functional block performs thedetection of the energy of a received symbol, an energy comparisonfunctional block is operable to perform comparison of the detectedenergy to a predetermined energy. This predetermined energy may beviewed as an expected energy at which the received symbols should be ator is expected to be at.

When a difference between the detected energy of the symbol exceeds athreshold (that may be programmable or adaptively determined in realtime in response to operating conditions or some other inputs), thenthis interference compensation functionality includes a functional blockthat is operable to perform selective weighting (as necessary) ofsymbols (or the individual bits of those symbols). This may be performedbased on the difference between the detected energy and thepredetermined energy. For example, when the energy is greater than thepredetermined energy by a particular threshold, then that may be used toindicate a high likelihood of a symbol collision, and that symbol may bede-weighted before performing decoding processing of the symbol (e.g.,in a decoder—one embodiment of which is a Viterbi decoder).

After the functionality of this diagram has bee performed, then theselectively modified symbol(s) and/or bits of those symbols are providedto a decoder for making best estimates of the information bits containedtherein. By selective modification, it is noted that some of the symbols(or some of the bits) may not undergo any de-weighting, but rather bepassed to the decoder without any modification at all. However, in thepresence of some interference, de-weighting may be performed to thesymbol or the individual bits of those symbols.

FIG. 18 is a diagram illustrating an embodiment of a 3^(rd) orderelliptical LPF (Low Pass Filter) employed at a transmitter and areceiver (or a transceiver) according to the invention. Above, it isnoted that the performance of a piconet operating according to theinvention will typically be limited only by the out of band roll off andfront end range (e.g., the radio front end and the filtering performedtherein) of a device operating within such a piconet. That is to say,the filter shape largely determines the degree of interferencerejection. Higher-order filters could substantially increase the ISRrange of such a system.

The LPF shown in this diagram was employed. It is however noted thateven better filters that may be designed can be implemented to providefor even better performance.

FIG. 19 is a diagram illustrating another embodiment of a piconetoperable device that supports functionality of interference compensationcapitalizing on structured interference (showing PHY (physical layer),MAC (Medium Access Controller), and higher protocol layers) according tothe invention. A piconet operable device is included within a piconet.This piconet operable device includes a PHY (physical layer) thatcommunicatively couples to a MAC (Medium Access Controller). The MACs ofthe devices may also communicatively couple to 1 or more even higherapplication layers within the piconet operable device. The MAC and thehigher application layers may be viewed as being the higher protocollayers (e.g., above the PHY) within the respective piconet operabledevice. The PHY is operable to support a physical interconnection linkto 1 or more other devices within a piconet.

When compared to a prior art MAC, the MAC of the piconet operable devicemay be viewed as being a modified protocol layer, in that, the MACincludes functionality to perform interference compensation based on theestimation of the location and level of the interference of the receivedsignal. In an alternative embodiment, the MAC of the piconet operabledevice may be viewed as being a modified protocol layer, in that, theMAC may include functionality to perform interference compensation thatcapitalizes on the properties of the structured interference that mayresult from symbol collisions when operating using the combination ofSH-OFDM and reduced PRF (Pulse Repetition Frequency) when compared toprior art piconet systems.

This interference compensation functionality is operable to performsymbol energy detection of symbols extracted from a signal received bythe piconet operable device. After performing the detection of theenergy of a received symbol, the detected energy is compared to apredetermined energy and/or estimated energy. When a difference betweenthe detected of the symbol exceeds a threshold (that may be programmableor adaptively determined), then this interference compensationfunctionality may then perform selective de-weighting of symbol. In oneexample, when the detected energy of the symbol exceeds a predeterminedthreshold (e.g., when the detected energy of the symbol is greater thanthe predetermined energy by the threshold) then the symbol isappropriately de-weighted before being passed to a decoder for decodingprocessing. In another example, when the interference level isrelatively much higher than the threshold, then the interferenceaffected bits may be treated as erasures.

FIG. 20, FIG. 21, FIG. 22, and FIG. 23 are flowcharts illustratingvarious embodiments of methods for receive processing in a piconetoperable device according to the invention.

Referring to the FIG. 20, the method involves receiving a signal thathas been transmitted using a single carrier (e.g., single carrierfrequency). Then, the method involves detecting an energy (or a power)of 1 or more symbol(s) within signal. Then, the method involvescomparing the energy (or the power) of 1 or more symbol(s) to apredetermined (or an expected) energy (or power).

Then, a decision is made. It is then determined whether the energy (orthe power) of the 1 or more symbol(s) is greater than the predetermined(or the expected) energy (or power). A threshold may be used to makethis comparison, and the threshold may be programmable or adaptive(e.g., based on operating conditions or some other operationalparameter).

If the energy (or the power) of the 1 or more symbol(s) is greater thanthe predetermined (or the expected) energy (or power), then this isindicative of a likely symbol collision. The symbol's energy (or power)is appropriately de-weighted, and that de-weighted symbol is thenprovided to a decoder for decoder processing. However, if the energy (orthe power) of the 1 or more symbol(s) is not greater than thepredetermined (or the expected) energy (or power), then the methodinvolves providing the symbol(s) to decoder for decoder processing.

This providing of the either the de-weighted symbols or the unmodifiedsymbols to the decoder for decoder processing may be viewed as beingproviding selectively weighted symbol(s) to decoder. That is to say,some of the symbols are de-weighted and some are not (hence, the termselectively de-weighted symbols. The method then involves decoding thede-weighted symbol or the unmodified symbol to make best estimates of atleast one information bit contained within the originally receivedsymbol.

Referring to the FIG. 21, the method involves receiving a signal thathas been transmitted using a single carrier and performingpre-processing thereon. The method then involves detecting collisionswithin that received and pre-processed signal. When no collision isdetected in the received and pre-processed signal, then the received andpre-processed signal is provided to a decoder to perform decoding tomake best estimates of at least one information bit contained therein.

However, when a collision is detected in the received and pre-processedsignal, then the method involves estimating a location and a level(e.g., magnitude) of those one or more collisions. This may involve alsoestimating the interference power per bit of the symbols that have beenextracted from that signal during pre-processing. The method theninvolves categorizing the level of interference associated withcollisions. This categorization may be viewed as being into a firstlevel of interference (very high-level interference) and a second levelof interference (medium-level interference).

The method then involves de-weighting the input to decoder based onlevel of that categorized interference. Two different de-weightingfactors may be employed based on the level of interference that has beendetected and categorized. For example, when the difference between theenergy of the symbol and the predetermined energy level exceeds a firstthreshold, then the method may involve selectively de-weighting thesymbol according to a first de-weighting factor and providing thede-weighted symbol to a decoder for subsequent decoding. When thedifference between the energy of the symbol and the predetermined energylevel exceeds a second threshold, then the method may involveselectively de-weighting the symbol according to a second de-weightingfactor and providing the de-weighted symbol (according to this differentde-weighting factor) to the decoder for subsequent decoding. When thedifference between the energy of the symbol and the predetermined energylevel does not exceed any threshold, the method may simply involveproviding the symbol to the decoder. Moreover, the method mayspecifically treat these various degrees of interference independently.For example, for the first level of interference (very high-levelinterference), the method involves treating the affected bits aserasures. For the second level of interference (medium-levelinterference), the method involves de-weighting input to decoder basedon the level (e.g., magnitude) of that interference. It is note that forthe second level of interference (medium-level interference), the degreeof de-weighting is performance based on the relative degree of thatinterference (e.g., based on the estimate of the interference). But whenthe level of interference exceeds a relatively high threshold (which maybe selected by a user) such as the first level of interference (veryhigh-level interference), those affected bits are simply treated aserasures and not appropriately de-weighted.

Referring to the FIG. 22, the method involves receiving a firstcontinuous time signal that has been transmitted using a single carrier.The method then involves frequency hopping mixing the first continuoustime signal thereby generating a second continuous time signal. This isperformed in accordance with the manner in which a transmitted signalwas frequency hopping mixed at a transmit end of a communicationchannel. The method then involves sampling the second continuous timesignal (e.g., using an ADC) thereby generating a discrete time signaland extracting I, Q (In-phase, Quadrature) components there from. Themethod then involves demodulating the I, Q components and performingsymbol mapping of the I, Q components thereby generating a sequence ofdiscrete-valued modulation symbols. The method then involves detectingand estimating the location and the level (e.g., magnitude) ofinterference associated with collisions. The method then involvestreating bits affected by very high-level interference as erasures. Themethod then involves selectively de-weighting bits affected bymedium-level interference based on level (e.g., magnitude) ofinterference. The method then involves de-interleaving de-weighted LLR.The method then involves decoding the appropriately de-interleavingde-weighted LLR thereby making best estimates of information bitscontained therein.

Referring to the FIG. 23, the method involves receiving a firstcontinuous time signal that has been transmitted using a single carrier.The method then involves frequency hopping mixing the first continuoustime signal thereby generating a second continuous time signal. Themethod then involves sampling the second continuous time signal (e.g.,using an ADC) thereby generating a discrete time signal and extractingI, Q (In-phase, Quadrature) components there from. The method theninvolves demodulating the I, Q components and performing symbol mappingof the I, Q components thereby generating a sequence of discrete-valuedmodulation symbols. The method then involves calculating LLR (LogLikelihood Ratio) of symbols of sequence of discrete-valued modulationsymbols. The method then involves de-weighting LLR by multiplying theLLR by inverse of square of the RMS (Root Mean Square) of level (e.g.,magnitude) of interference. The method then involves de-interleavingde-weighted LLR. The method then involves decoding appropriatelyde-interleaving de-weighted LLR thereby making best estimates ofinformation bits contained therein.

As mentioned above, there are many possible variations on approached andmethods to estimate the interference power level. Some of these possibleapproaches are illustrated in the following diagrams and describedbelow.

FIG. 24A, FIG. 24B, and FIG. 24C are flowcharts illustrating variousembodiments of methods for estimating a level (e.g., magnitude) ofinterference of a signal for use in performing interference compensationaccording to the invention.

Referring to the FIG. 24A, the method involves measuring totalinstantaneous power. The method then involves averaging signal power.The method then involves subtracting expected signal power (based onpreviously-obtained channel estimate or reference signal powermeasurement) from the average signal power thereby generatingde-weighting factor that is used in performing interferencecompensation.

Referring to the FIG. 24B, the method involves estimating starting andending points of interference. The method then involves adjusting thede-weighting factor based on duration and magnitude of interference.This is a relatively easier approach to estimating a level ofinterference of a signal for use in performing interference compensationcompared to the approach described just above.,

Referring to the FIG. 24C, the method is a one step method approach thatinvolves estimating the level (e.g., magnitude) of interference based onprior knowledge of structured nature of the interference itself. Asdescribed above in various embodiments, the manner in which the variousSOPs (Simultaneously Operating Piconets) operate using frequency hoppingapproaches, the manner and type of interference they may experience canexhibit a “structured” type nature. Knowledge of this can be used toestimate the level and location of the interference within a signalreceived by a piconet operable device.

This is a completely straight-forward approach to estimating a level ofinterference of a signal for use in performing interferencecompensation.

It is also noted that various methods may be performed, in accordancewith the invention, in a manner similar to the operation andfunctionality of the various system and/or apparatus embodimentsdescribed above. In addition, such methods may be viewed as beingperformed within any of the appropriate system and/or apparatusembodiments (communication systems, communication transmitters,communication receivers, communication transceivers, and/orfunctionality described therein) that are described above withoutdeparting from the scope and spirit of the invention.

The proposed systems and methods provide for a much improved performancewhen compared to any of the current proposals in the context of SOPswithin relatively close proximity with one another. For example, in a3-band system with 2 SOPs using different hopping sequences, one out ofevery three bits may be erased. In a 7-band system with 4 SOPs, threeout of seven bits may be erased. It is critical to choose codes andinterleavers such that after collisions, the surviving bits still employa strong code. These effects are described in greater detail within thereference [3] mentioned above.

When compared to the prior art approaches to deal with interferencegenerated by SOPs within relatively close proximity with one another,the proposed system dramatically improves performance in the presence ofclose SOPs, without sacrificing frequency diversity, without increasingthe peak transmitted power, and without requiring other piconets to usethis mode. In addition, it offers a simple low-power transmission modesuitable for applications where the power of the transmitter must beminimized.

In view of the above detailed description of the invention andassociated drawings, other modifications and variations will now becomeapparent. It should also be apparent that such other modifications andvariations may be effected without departing from the spirit and scopeof the invention.

1. A method for operating a piconet operable device, the methodcomprising: receiving a signal that includes a symbol; detecting anenergy of the symbol; comparing the energy of the symbol to apredetermined energy or to an estimated energy; determining whether adifference between the energy of the symbol and the predetermined energyexceeds at least one threshold from among a plurality of thresholds orwhether a difference between the energy of the symbol and the estimatedenergy exceeds at least one threshold from among a plurality ofthresholds; when the difference exceeds a first threshold of theplurality of thresholds and no other threshold of the plurality ofthresholds, selectively de-weighting the symbol according to a firstde-weighting factor and providing the de-weighted symbol to a decoder;when the difference exceeds the first threshold and a second thresholdof the plurality of thresholds and no other threshold of the pluralityof thresholds, selectively de-weighting the symbol according to a secondde-weighting factor and providing the de-weighted symbol to a decoder;and when the difference does not exceed any threshold of the pluralityof thresholds, providing the symbol to the decoder.
 2. The method ofclaim 1, further comprising: when the difference exceeds the eachthreshold of the plurality of thresholds, treating interference affectedbits of the symbol as erasures.
 3. The method of claim 1, wherein: thepiconet operable device is a first piconet operable device that operateswithin a first piconet that substantially occupies a first region; asecond piconet operable device operates within a second piconet thatsubstantially occupies a second region; and the first region and thesecond region occupy at least a portion of common space.
 4. The methodof claim 3, wherein: the symbol is a first symbol that collides with asecond symbol that is received by the second piconet operable devicebefore being received.
 5. The method of claim 3., wherein: collisionsbetween symbols within the first piconet and symbols within the secondpiconet occur according to a structured interference pattern.
 6. Themethod of claim 5, wherein the structured interference pattern is apredetermined structured interference pattern; and further comprising:at least one threshold from among the plurality of thresholds based onthe predetermined structured interference pattern.
 7. The method ofclaim 1, further comprising: estimating at least one of a location and alevel of interference of the symbol using the detected energy of thesymbol.
 8. The method of claim 1, further comprising: when thedifference exceeds the first threshold of the plurality of thresholdsand no other threshold of the plurality of thresholds, selectivelyde-weighting the symbol according to a first de-weighting factor andde-interleaving the de-weighted symbol before providing the de-weightedsymbol to the decoder.
 9. The method of claim 1, further comprising:when the difference exceeds the first threshold and the second thresholdof the plurality of thresholds and no other threshold of the pluralityof thresholds, selectively de-weighting the symbol according to thesecond de-weighting factor and de-interleaving the de-weighted symbolbefore providing the de-weighted symbol to the decoder.
 10. The methodof claim 1, further comprising: when the difference does not exceed anythreshold of the plurality of thresholds, de-interleaving the symbolbefore providing the symbol to the decoder.
 11. A piconet operabledevice, the device comprising: a radio front end that receives andfilters a continuous time signal; an ADC (Analog to Digital Converter)that samples the received and filtered continuous time signal therebygenerating a discrete time signal and extracting I, Q (In-phase,Quadrature) components there from; a demodulator that receives the I, Qcomponents and performs symbol mapping of the I, Q components therebygenerating a sequence of discrete-valued modulation symbols; wherein thedemodulator estimates at least one of a location and a level ofinterference associated with a collision within a symbol of the sequenceof discrete-valued modulation symbols; wherein the demodulatorcategories the level of the interference into at least two categorizes;when the level of the interference is categorized into a first categoryof the at least two categorizes, the demodulator treats interferenceaffected bits of the symbol as erasures thereby generating a firstdemodulator output symbol; when the level of the interference iscategorized into a second category of the at least two categorizes, thedemodulator selectively de-weights interference affected bits of thesymbol according to a de-weighting factor thereby generating a seconddemodulator output symbol; and a decoder that decodes the firstdemodulator output symbol or the second demodulator output symbol tomake best estimates of the at least one information bit containedtherein.
 12. The device of claim 1, wherein: the demodulator estimatesinterference associated with the collision within the symbol on a powerper bit basis.
 13. The device of claim 11, wherein: the location ofinterference associated with the collision within the symbol is used toidentify the interference affected bits of the symbol.
 14. The device ofclaim 11, wherein: demodulator is implemented as a basebandprocessor/MAC (Medium Access Controller) within the piconet operabledevice.
 15. The device of claim 11, wherein: the piconet operable deviceis a first piconet operable device that operates within a first piconetthat substantially occupies a first region; a second piconet operabledevice operates within a second piconet that substantially occupies asecond region; and the first region and the second region occupy atleast a portion of common space.
 16. The device of claim 15, wherein:the symbol is a first symbol that collides with a second symbol that isreceived by the second piconet operable device before being received.17. The device of claim 15, wherein: collisions between symbols withinthe first piconet and symbols within the second piconet occur accordingto a structured interference pattern.
 18. The device of claim 17,wherein: the structured interference pattern is a predeterminedstructured interference pattern; and the demodulator estimates at leastone of the location and the level of interference associated with thecollision within the symbol based on the predetermined structuredinterference pattern.
 19. The device of claim 11, wherein: thedemodulator estimates the level of interference associated with thecollision within the symbol by measuring a total instantaneous power ofthe continuous time signal associated with the symbol, averaging a powerof the continuous time signal associated with the symbol, andsubtracting an expected reference signal power associated with thesymbol from a previously obtained channel estimate or power measurementof the continuous time signal associated with the symbol.
 20. The deviceof claim 11, wherein: when the level of the interference is categorizedinto a third category of the at least two categorizes, the decoderdirectly decodes the symbol to make best estimates of the at least oneinformation bit contained therein.
 21. A piconet operable device, thedevice comprising: a radio front end that receives and filters a firstcontinuous time signal that has been transmitted using a single carrierfrequency; a frequency hopping mixer that mixes the first continuoustime signal thereby generating a second continuous time signal; a LPF(Low Pass Filter) that filters the second continuous time signal; an ADC(Analog to Digital Converter) that samples the filtered, secondcontinuous time signal thereby generating a discrete time signal andextracting I, Q (In-phase, Quadrature) components there from; ademodulator that receives the I, Q components and performs symbolmapping of the I, Q components thereby generating a sequence ofdiscrete-valued modulation symbols; wherein the demodulator determinesan average total signal power of a symbol of the sequence ofdiscrete-valued modulation symbols; wherein the demodulator subtracts areference signal power estimate from the average total signal power ofthe symbol to generate a de-weighting factor; the demodulatorselectively de-weights interference affected bits of the symbolaccording to the de-weighting factor thereby generating a demodulatoroutput symbol; and a decoder that decodes the demodulator output symbolto make best estimates of the at least one information bit containedtherein.
 22. The device of claim 21, wherein: the demodulator estimatesat least one of a location and a level of interference associated with acollision within the symbol of the sequence of discrete-valuedmodulation symbols; the demodulator categories the level of theinterference into at least two categorizes; when the level of theinterference is categorized into a first category of the at least twocategorizes, the demodulator treats interference affected bits of thesymbol as erasures thereby generating a first demodulator output symbol;and when the level of the interference is categorized into a secondcategory of the at least two categorizes.
 23. The device of claim 22,wherein: when the level of the interference is categorized into a thirdcategory of the at least two categorizes, the decoder directly decodesthe symbol to make best estimates of the at least one information bitcontained therein.
 24. The device of claim 22, wherein: the demodulatorestimates interference associated with the collision within the symbolon a power per bit basis.
 25. The device of claim 22, wherein: thelocation of interference associated with the collision within the symbolis used to identify the interference affected bits of the symbol. 26.The device of claim 21, wherein: the piconet operable device is a firstpiconet operable device that operates within a first piconet thatsubstantially occupies a first region; a second piconet operable deviceoperates within a second piconet that substantially occupies a secondregion; and the first region and the second region occupy at least aportion of common space.
 27. The device of claim 26, wherein: the symbolis a first symbol that collides with a second symbol that is received bythe second piconet operable device before being received.
 28. The deviceof claim 26, wherein: collisions between symbols within the firstpiconet and symbols within the second piconet occur according to astructured interference pattern.
 29. The device of claim 28, wherein:the structured interference pattern is a predetermined structuredinterference pattern; and the demodulator estimates at least one of alocation and a level of interference associated with a collision withinthe symbol of the sequence of discrete-valued modulation symbols basedon the predetermined structured interference pattern.
 30. The device ofclaim 21, further comprising: an interleaver that interleaves thedemodulator output symbol before the decoder decodes the demodulatoroutput symbol to make best estimates of the at least one information bitcontained therein.